Quiz - Data Representation

Instructions

Answer all 15 questions to test your knowledge of characters, images, and sound representation. You'll see your results at the end.

Topics covered: Character sets (ASCII, Unicode), image file sizes (resolution, colour depth, metadata), sound files (sample rate, bit depth, duration)

Question 1

What is a character set?

A collection of fonts for displaying text A collection of characters with their assigned binary codes A keyboard layout for typing A type of file format for text documents

Explanation: A character set defines which characters are available and assigns a unique binary code to each one.

Question 2

ASCII uses 8 bits per character. How many different characters can it represent?

8 128 256 65,536

Explanation: With n bits, you can represent 2^n characters. 2^8 = 256 characters.

Question 3

In ASCII, if 'A' = 65, what is the code for 'C'?

63 66 67 68

Explanation: ASCII characters are logically ordered. C is 2 positions after A, so 65 + 2 = 67.

Question 4

Which character set would you choose for a website displaying Japanese, Arabic, and emojis?

ASCII (smaller files) Unicode (supports all languages) Either would work equally well A custom character set

Explanation: ASCII only supports 256 characters (English letters and basic symbols). Unicode supports over 140,000 characters including all world languages and emojis.

Question 5

A text file contains 1,500 characters. Using Unicode (16-bit), what is the file size in bytes?

1,500 bytes 3,000 bytes 12,000 bytes 24,000 bytes

Explanation: 1,500 × 16 = 24,000 bits. 24,000 ÷ 8 = 3,000 bytes. (Or simply: 16 bits = 2 bytes per character, so 1,500 × 2 = 3,000)

Question 6

What is a pixel?

A type of image file format The smallest element of a digital image A measurement of colour depth A type of metadata

Explanation: A pixel (picture element) is the smallest single point in a digital image. Each pixel has a specific colour represented by a binary code.

Question 7

An image has a colour depth of 24 bits. How many different colours can each pixel display?

24 colours 256 colours 65,536 colours 16.7 million colours

Explanation: Number of colours = 2^colour depth. 2^24 = 16,777,216 (approximately 16.7 million colours, known as "true colour").

Question 8

What is the file size of a 800 × 600 pixel image with 8-bit colour depth?

480,000 bytes 960,000 bytes 1,440,000 bytes 3,840,000 bytes

Explanation: Pixels = 800 × 600 = 480,000. Bits = 480,000 × 8 = 3,840,000. Bytes = 3,840,000 ÷ 8 = 480,000 bytes.

Question 9

Which of these is NOT typically stored in image metadata?

Image width and height The actual pixel colour data Date the image was created Camera settings

Explanation: Metadata is "data about data" - information about the image (dimensions, date, camera settings). The actual pixel colour values are the main image data, not metadata.

Question 10

What does "sample rate" measure in digital audio?

The volume of the audio How many samples are taken per second The length of the audio file The number of speakers used

Explanation: Sample rate is measured in Hertz (Hz) and indicates how many times per second the sound wave is sampled. CD quality is 44,100 Hz (44.1 kHz).

Question 11

What is the standard sample rate for CD quality audio?

8,000 Hz 22,050 Hz 44,100 Hz 96,000 Hz

Explanation: CD quality audio uses 44,100 Hz (44.1 kHz) sample rate with 16-bit depth.

Question 12

What effect does increasing the bit depth have on a sound file?

Makes the audio play faster Increases quality (more volume levels) but larger file Decreases the file size Adds more audio channels

Explanation: Bit depth determines how many different volume levels can be recorded. Higher bit depth = more precise audio with better dynamic range, but larger files.

Question 13

A mono audio file is 5 MB. What size would the same recording be in stereo?

2.5 MB 5 MB 10 MB 15 MB

Explanation: Stereo has 2 channels (left and right), each storing separate audio data. Stereo file size = mono × 2 = 10 MB.

Question 14

Calculate the file size of a 10-second mono sound at 44,100 Hz and 16-bit depth.

441,000 bytes 705,600 bytes 882,000 bytes 1,764,000 bytes

Explanation: Bits = 44,100 × 16 × 10 = 7,056,000 bits. Bytes = 7,056,000 ÷ 8 = 882,000 bytes.

Question 15

Which statement best describes the trade-off in data representation?

Higher quality always means faster processing Higher quality requires more storage space File size has no relationship to quality Smaller files always have better quality

Explanation: The universal trade-off: more bits per unit (character, pixel, sample) = better quality/more options, but larger file sizes. This applies to text, images, and sound.

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